Just got this email back from Mike at Callowhill:
It weighs less than a typical Fender 4 string, the OBS contouring, size, and eq route clocks it in at ten lbs, other OBS' have clocked in at just over 5 lbs. Tim carved it out of a solid block of acrylic, and added a fiber optic bay keyed into a Wittman tuner so it actually changes color but is only visible in dark venues. It has a (eleven?) piece neck of myrtle, wenge, and maple with a Brazilian rosewood fingerboard, and a custom 28 fret neck that completes the pickup route. The headstock has a jigsaw acrylic "binding" that bolts into the headstock with visible screws, and the logo glows in the dark. Pretty strange.
Personally, I think it's a lot cooler than when I first saw it. To say that it's lighter than a typical fender and be acrylic, that had to take some engineering. Makes me want a Callowhill now more than ever!